C#编写数据库 SqlHelper

static class SqlHelper
{
public static readonly string connstr = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;

public static int ExecuteNonQuery(string sql,
params SqlParameter[] parameters)
{
using (SqlConnection conn = new SqlConnection(connstr))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameters);
return cmd.ExecuteNonQuery();
}
}
}

public static object ExecuteScalar(string sql,
params SqlParameter[] parameters)
{
using (SqlConnection conn = new SqlConnection(connstr))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameters);
return cmd.ExecuteScalar();
}
}
}

public static DataTable ExecuteDataTable(string sql,
params SqlParameter[] parameters)
{
using (SqlConnection conn = new SqlConnection(connstr))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = sql;
cmd.Parameters.AddRange(parameters);

DataSet dataset = new DataSet();
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
adapter.Fill(dataset);
return dataset.Tables[0];
}
}
}

public static object FromDbValue(object value)
{
if (value == DBNull.Value)
{
return null;
}
else
{
return value;
}
}

public static object ToDbValue(object value)
{
if (value == null)
{
return DBNull.Value;
}
else
{
return value;
}
}
}